The present invention refers to a sealing device.
There are known bearings for a vehicle wheel hub provided with special vents and sealing devices for inflating into the tire air pressurized by means of a source of pressurized air mounted on board of the vehicle. These solutions allow to adjust and/or monitor the air pressure in the tires.
FIG. 1 of the accompanying drawings shows a bearing of the aforementioned type, known, for example, from U.S. Pat. No. 5,484,213. The bearing of FIG. 1 comprises an outer race 1, an inner race 2 formed by two axially adjacent half-races, and two sets of bearing balls 3. In a radial plane located between the two sets of balls 3 there are several outer radial channels 6 passing through the bearing outer race 1, and several inner radial channels 7 formed through the bearing inner race 2.
Mounted in the annular space defined by the outer race 1, the inner race 2 and the two sets of balls 3 are two annular sealing units 9 that allow pressurized air to pass through the outer 6 and inner 7 channels of the bearing. The two sealing units are facing one another axially and disposed symmetrically with respect to the radial plane in which the channels 6 and 7 of the bearing unit lie. Each sealing unit 9 comprises a metal reinforcement 10 on which a flexible gasket 11 is over-molded. The reinforcement 10 is formed by a sheet metal bent so as to have an axial cylindrical wall that is axially fixed to the outer race 1 of the bearing and a radial wall for stiffening the gasket 11. This gasket forms an airtight sealing lip 12 that slidingly contacts a contact surface 13 of the inner race 2 of the bearing. The two sealing units 9 so arranged delimit an intermediate annular chamber 14. Air pressurized by a pressurized air source mounted on board of the vehicle, which may be part of an automatic system or a system controlled by the driver, passes through special ducts obtained in the suspension standard of the wheel where the bearing is housed, passes through the outer channels 6, in the intermediate annular chamber 14, through the inner channels 7, and from here is conveyed through other ducts to the wheel rim and finally the tire.